This is a generous rewriting of history on Barr's legacy in the Trump administration.
Not only did Barr interfere with the Mueller investigation & report to protect Trump and keep the American people ignorant of the Trump campaign's crimes, but he also interfered in the Flynn & Stone prosecutions in direct opposition to the DOJ attorneys running the cases to reinforce the rule of law and, like Mueller's investigators, perform the oath sworn duty they made to the American people.
Congressional oversight was the only way to confront Barr, force him to explain his actions and work to hold him accountable.
The fact that he finally awoke from his combined imperial Presidency and Trump fever dream and drew the line at outright insurrection and treason, while admirable, is a low Barr (pun intended) for someone in a critical position of Attorney General.
It was good that he testified for the January 6th committee and put on the record the lengths to which Trump and his sycophants were willing to go to steal the 2020 election, but, like Pence, that does not erase the legal and constitutional lines Barr crossed earlier that led to those actions.
Trump assumed Barr and Pence were his "guys" because up to that point they both had been in every way.
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On the issue of congressional oversight being mostly gotcha politics and TV ready talking points, I agree with you and believe Congress needs to change the format and procedures for hearings to facilitate real discovery and discussion.